The invention relates generally to semiconductor fabrication and, in particular, to methods of fabricating an electrical fuse and device structures for an electrical fuse.
Programmable devices, such as electrical fuses (efuses) and antifuses, are widely-used elements found in various programmable integrated circuits, such as redundancy circuits of dynamic random access memories and static random access memories, programmable logic devices (PLDs), I/O circuits, chip identification circuits, etc. Electrical fuses may also constitute elements of a built-in self-repair system for a chip that constantly monitors the chip functionality. If needed, the self-repair system can automatically activate one or more electrical fuses to respond to a change in the monitored conditions.
An electrical fuse includes two comparatively large plates defining an anode and a cathode, as well as a lengthy and narrow fuse link connecting the anode and cathode. When manufactured, an electrical fuse is initially closed. Electrical fuses may be dynamically programmed in real time by passing an electrical current of relatively high density through the fuse link. Large programming currents may cause the fuse link to rupture by an abrupt temperature increase and permanently open. Smaller programming currents may cause a controlled electromigration of the material constituting the fuse link. Both programming modes serve to elevate the resistance of a programmed electrical fuse in comparison with the intact electrical fuse in its unprogrammed state.
Improved structures for an electrical fuse and improved methods of manufacturing electrical fuses are needed.